>Sir John Cockcroft, leading the project team, was sufficiently alarmed to order the filters. They could not be installed at the base as construction of the chimneys had already begun, and were constructed on the ground then winched into position at the top once the chimney's concrete had set.[42] They became known as "Cockcroft's Folly" as many regarded the delay they caused and their great expense to be a needless waste. During the fire the filters trapped about 95% of the radioactive dust and arguably saved much of northern England from becoming a nuclear wasteland. Terence Price said "the word folly did not seem appropriate after the accident".

You've got to love the British understatement! Having said that, this was really at the start of the nuclear age and came about through the UK being excluded from US nuclear projects despite having contributed to the Manhattan Project under the incorrect assumption technology would be shared after the war. Windscale was built because Britain needed the atomic bomb to prevent its post-war decline making it geopolitically irrelevant and needed it before the US and Soviet Union banned further testing. There's no way anything like that would be built today by any sane government knowing what we do now.